[PATCH v2] s390: vsie: Use effective CRYCBD.31 to check CRYCBD validity

From: Pierre Morel
Date: Mon Feb 11 2019 - 04:21:00 EST


When facility.76 MSAX3 is present for the guest we must issue a validity
interception if the CRYCBD is not valid.

The bit CRYCBD.31 is an effective field and tested at each guest
level and has for effect to mask the facility.76

It follows that if CRYCBD.31 is clear and AP is not in use we do not
have to test the CRYCBD validatity even facility.76 is present in the
host.

Fixes: 6ee74098201b ("KVM: s390: vsie: allow CRYCB FORMAT-0")
Cc: stable@xxxxxxxxxxxxxxx

Signed-off-by: Pierre Morel <pmorel@xxxxxxxxxxxxx>
Reported-by: Claudio Imbrenda <imbrenda@xxxxxxxxxxxxx>
Acked-by: David Hildenbrand <david@xxxxxxxxxx>
---
arch/s390/kvm/vsie.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/s390/kvm/vsie.c b/arch/s390/kvm/vsie.c
index a153257..d62fa14 100644
--- a/arch/s390/kvm/vsie.c
+++ b/arch/s390/kvm/vsie.c
@@ -297,7 +297,7 @@ static int shadow_crycb(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page)
scb_s->crycbd = 0;

apie_h = vcpu->arch.sie_block->eca & ECA_APIE;
- if (!apie_h && !key_msk)
+ if (!apie_h && (!key_msk || fmt_o == CRYCB_FORMAT0))
return 0;

if (!crycb_addr)
--
2.7.4